Cadence Web UI

Cadence is a distributed, scalable, durable, and highly available orchestration engine we developed at Uber Engineering to execute asynchronous long-running business logic in a scalable and resilient way.

This web UI is used to view workflows from Cadence, see what's running, and explore and debug workflow executions.

Getting Started

Configuration

Set these environment variables if you need to change their defaults

Running locally

cadence-web requires node v10.22.1 or greater to be able to run correctly. cadence-web uses all the standard npm scripts to install dependencies, run the server, and run tests. To provide a consistent environment we recommend using docker in development. To start local server with live reload on code change you can run:

docker-compose up

For development we recommend using VSCode with Remote Containers plugin. We provide a default configuration for remote container using docker-compose.

For development and contributing to cadence-web, please see the contributing guide.

You may also use docker by pulling ubercadence/web. It is also included in the Cadence server's local docker setup.

API

If you need to extend cadence-web to add middleware to the server, you can install cadence-web as a dependecy, and it will export the Koa web server that has not yet been started or configured. It includes an additional init function that will then compose the built-in middleware. This gives you an option to add middleware before or after you call init so it will add the middleware at the beginning or the end of the chain, respectively.

init(options)

All options are optional.

useWebpack: If true, starts webpack and adds the middleware, otherwise if false, it assumes the UI bundle was already built and serves it statically. Defaults to process.env.NODE_ENV === 'production'.

logErrors: If true, thrown errors are logged to console.error. Defaults to true.

For example, here is how you would add a request count metric using uber-statsd-client:

var app = require('cadence-web')
var createStatsd = require('uber-statsd-client')
var sdc = createStatsd({
    host: 'statsd.example.com'
})

app.use(async function(ctx, next) {
  sdc.increment('http.request')
  await next()
})
.init()
.listen(7000)

The webpack configuration is also exported as webpackConfig, and can be modified before calling init().

Licence

MIT License, please see LICENSE for details.